Editor’s note: This article is part of a series on election integrity. Read another perspective here.

The “Motor Voter” law didn’t enter this world alone. It was twins.

In 1993, Congress passed and President Bill Clinton signed the National Voter Registration Act, which put new federal requirements on the states to do two things: “increase the number of eligible citizens who register to vote,” and “protect the integrity of the electoral process.” The law was very specific about how these objectives were to be accomplished.

States had to offer voter registration opportunities to people when they applied for or renewed a driver’s license, at government offices that provided public assistance and by mail.

States also were required to keep their voter registration lists “accurate and current” by identifying voters who had become ineligible to vote because they had died or moved. The states’ programs for voter list maintenance had to meet specific standards: the procedures had to be uniform, non-discriminatory, in compliance with the Voting Rights Act and not conducted within 90 days of a federal election.

While states can take different approaches, the law lists one option for identifying voters who have moved. States may use the U.S. Postal Service’s change-of-address service and send voters a written notice asking if they’re still at their registered address. The notice must explain that to keep the voter registration active, the voter must return the included prepaid postcard or must vote at least once during the time period that includes the next two federal elections.

Ohio used that process, but up to 40 percent of people who move don’t use the change-of-address service, according to the Postal Service. So Ohio added a supplemental process. If someone didn’t vote in any election for two years, the state sent them the written notice and the prepaid postcard. If they didn’t return the card and they didn’t vote for four years (a total of six years of non-voting), the state canceled their registration.

In 2016, Ohio was sued by civil rights groups on the grounds that this is voter suppression.

Last week, the U.S. Supreme Court ruled 5-4 that Ohio’s process is not only legal, but mandatory.

Under federal law — both the National Voter Registration Act and the 2002 Help America Vote Act — “failure to vote” can’t be the only reason for canceling a registration. Five justices thought the state’s written notice, combined with the lack of voting, was exactly what the law both allowed and required. Four justices thought Ohio’s supplemental process illegally used “failure to vote” as the trigger for canceling a registration.

But is it discriminatory against anybody? Is it voter suppression?

There is a history here. The 1965 Voting Rights Act put some states and local jurisdictions under federal oversight, barring them from making changes to their election laws without advance federal approval.

But in 2013, the U.S. Supreme Court lifted that restriction. Chief Justice John Roberts said Congress was free to impose restrictions again, but only if based on current data. In the Ohio case, no one made the claim that the state’s procedures were discriminatory.

This case could have an impact on California, currently being sued by Judicial Watch and the Election Integrity Project California for failing to maintain accurate and current voter rolls. According to the lawsuit, 11 counties have more registered voters than citizen voting-age residents. In Los Angeles County, which is also being sued, the voter registration rate is 144 percent, according to the lawsuit.

That would explain why voter turnout is so low in L.A. County. Statewide, voter turnout in the June 5 primary, as of June 14 with ballots still uncounted, was 32.3 percent. In L.A. County, turnout was 24 percent. But 24 percent of what? There are 5,149,461 registered voters in L.A. County. How many are phantoms?

We’d better find out. California is in the process of changing over to electronic voter registration and voting equipment, including a new remote voting system made by Dominion Voting, a privately held company headquartered in Toronto and Denver. Secretary of State Alex Padilla recently approved that equipment, with a paper ballot back-up, for limited use by military, overseas and disabled voters. The company’s website says ImageCast Remote is a system for telephone and internet voting.

The U.S. Department of Homeland Security says the Russian government tried to get into state voter registration databases in 2016, and in some cases succeeded. In the future, could hackers manipulate an electronic voting system and cast votes for inactive voters, undetected? Maybe they can do it already.

Federal law requires the states to maintain accurate and current voter lists. In 1993, that was part of a deal to expand voter registration opportunities. Today, it could be a matter of national security.